Failed range calculation left me stranded

We're on page 2, and I'm surprised no one has yet posted the link to the very lengthy post about this very subject, showing many people with this experience of the car shutting down with a few miles still left on the display.
Has your car shut down before it hits zero?

NO! Because it definitely wouldn't prevent this kind of thing from happening. Have you been around here for 4 to 5 years or so? Do you remember all of the old discussion of people trying to be all authoritative about stating exactly how many miles reserve there was below 0? Some people said 20. Some people said 17. And so (obviously, as humans do), people came to expect to be able to drive that far below 0 every time, and frequently planned to do exactly that.

And that led to things like this:
"Zero" means "Zero" - Caution about Vegas to LA trip!
...where someone tried to go below 0 and the car shut down only 4 miles below 0, and this was considered huge and shocking and something that people needed to be warned about! *facepalm*

So no, there doesn't need to always be a buffer below 0, because people will just take it for granted, and it won't do anything. And if 0 means 0, then don't be shocked or offended if you get within about 3 or 4 of it, and there's a problem. That's basically about 1kWh of energy. Out of a 70-some kWh pack, that's about 1.4% margin of error. Someone is going to be offended and angry that a battery meter (or any kind of fuel meter, for that matter) is not quite accurate down to less than 2%?!

 

One time I drove my former C-Max Energi 40 miles after the range estimate reading went to 0! That was a pucker inducing last leg of a road trip.

 

10% is my "mental buffer" and limit that means "zero". I once challenged the car and went circling around a supercharger and got down to 4% but then nerved out and plugged in. I just wanted to get a feeling that the car would still move with 5%. Now I know it does. I will check every year or so that that's still the case.

I generally make a plan to arrive with at least 10% at destination unless I'm facing some extenuating circumstance, in which case have a plan B (call a cab, be prepared to tow, etc.). If the on-board trip planner is projecting arrival with less than 10% I am worried, and look for ways to charge en route in case I have to.

I'd say if you have a routine need for more range you've under-bought the battery size, or EV are not ready for you. It's harder on the battery to be below 10% than it is to be above 90%.

 

My last car had a 14.5 gallon tank. It said low fuel after using about 9, and range estimate went to 0 miles after about 10.5 gallons. I knew I could get at least 120 miles after 0, maybe 150. I never ran out. (And lucky I didn't fry the fuel pump!)

I've been below 20 miles a few times in my MS, but I really don't like it. I have seen posts about running out above zero, so I watch the power restriction; never been down to 100kw restriction as Bjorn did.

 

Tesla could just not shut the car down until it reaches 0 miles. At 4 miles when it shutdown, there was plenty of energy left in the battery to limp along that last bit.

 

Maybe that's be cause it didn't leave them stranded on the side of the road

 

This is also why you should accelerate as slowly as possible when you get to this point. A sudden stab of the throttle could cause a shutdown.

 

Maybe they did build some conservatism into the Model 3, which is for the mass market. But in all the Model 3 thread estimating true range or battery pack size, do folks say, oh they built in 20 miles or a few % of buffer, good move? No, it's all, hey they hid some range at the top or bottom, why don't they let us use the full capacity? One car's buffer to ensure zero is zero, is another car's wasted capacity where zero is not zero....due to the variances in pack chemistry and voltages and balancing

 

When you stretch it below 5% SOC indicated the car will not charge the 12V battery anymore. Should you take your time before plugging in, park somewhere etc, then use HVAC/lights and other stuff that consumes power you can well find yourself stranded even if the car has more usable power in the main battery.

Another thing important is this far down on SOC the car seldom is, so it dosnet know the lay of the terrain and what the real bottom is. So rule is, keep a very keen eye on the powerlimiter, once it hits 20kw you really have no paddle left in that famous creek. 40kw and you`re kissing it.

 

And yes, a calibrated batterypack will have about 3-3,5kwh hidden below 0km range. Are you a gambling man? Many have been left stranded this way

 

When you get that low it is all about how well matched and balanced the modules are...

Only takes one module to be a bit weaker and a little extra load like a hill or acceleration and it will correctly shut down to protect the weakest module.

If you insist on trying to reach zero you will come up short sometimes, that isn't a fault or a miscalculation it is just physics and chemistry

 

I once reached 11 miles of range and considered myself at grave risk. The consequences of a Tesla shutdown are more consequential than an ICE running out of fuel. Cutting it closer leaves you at the mercy of an unknown algorithm.

 

I've driven my car down to 1% or 0% many times. Several times even below 0%. I actually aim for 5% or lower on road trips to save time at Superchargers. The key thing when the battery is low is to drive gently. Use the accelerator very carefully, keep the speed low, accelerate very carefully. If you push it hard the car will shut down much more likely.

 

And what exactly would the navigation show you on screen?

Did it show the drive was possible? Maybe you missed the warning message's...

 

That’s a little too close for comfort for me! And with the newer packs we are also throttled at the Supercharger when below 10%, so it may actually be counter productive for us to go to 0-5%. Haven’t done the math on it though.

 

Yes the newer packs start charging slower when below 10%. My old 85 pack starts charging at full power right from the start. Tesla did play around with the charge curves, though. In the beginning, when the 90 pack came out, they charged exactly like the 85. Full power from the beginning, then ramp down. Then they changed it to ramp up over the first 10% and for a short while my 85 did the same thing! That got fixed in a firmware update quickly, though.

But back on topic, in the last 5 years I have been here on this board I have seen maybe 3 or 4 posts about a car shutting down before it was at zero. One admitted he was going uphill pretty fast. OTOH I have seen countless posts of people cutting it very close and many reports of driving past zero. Overall Tesla is doing a fantastic job estimating range. But of course that is no help to someone that had their car shut down before zero.

 

I am not sure the OP used the navigation but just the battery display on the dash.

If he had used the navigation it would have provided him another input that would have factored in recent driving and elevation related energy. But that in itself could be problematic, at least as far as the recent energy consumption factor.

But at least it would have been another data point to consider.

 

Maybe the car could go into chill mode (and throw a notification to that fact)
when the range is in the 'danger area'?

 

When the battery is in a low state of charge you'll notice the consumption graph blocked off at the high end range, preventing massive acceleration. This is due to the voltage drop of a battery in a low SOC.

 

I guess your car didn't get the memo.


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